Common heating, ventilation, and air conditioning (HVAC) control projects are characterized by: 1) little time for manual tuning and maintenance; 2) installers that are not control engineers; 3) a commissioning during one season that leaves loops operating in other seasons; 4) a non-linear plant causing poor control at some operating points; and 5) disturbances that are significant. As a result of the small amount of time for manual tuning and maintenance, and the fact that installers are normally not control engineers, control loops are often not properly tuned. Even if the control loop is properly tuned, the control quality (loop performance) can deteriorate over time due to seasonal changes, plant non-linearity, hardware malfunctions, or disturbances. Consequently, the comfort level of the building is compromised, energy is wasted, and/or actuators prematurely wear out.